Field of the Invention
The present invention relates to a microbiological gas sampler. More particularly, the present invention is for a microbiological gas sampler for use in a controlled environment that includes an ergonomic top plate with concaved sidewalls. The concaved sidewalls allow both more positive contact when attempting to grasp the top plate and a reduction of the weight of the device.
Background of the Related Art
A controlled environment is an area which is designed, maintained, or controlled to prevent particle and microbiological contamination of products. Controlled environments include, for example, clean rooms and clean hoods. There are different levels of cleanliness in clean rooms, generally in the range of a Class 100 room (i.e., a room having no more than 100 particles of 0.5 micron and larger, per cubic foot of air), to a Class 10,000 clean room.
Clean rooms are used for a variety of purposes, such as in the manufacture of pharmaceutical products and electronics, such as semiconductors. Often, clean rooms are used to work on extremely expensive and complex products, and it is not unusual that there be millions of dollars worth of product in a clean room at any given time. Clean rooms have to maintain a high level of cleanliness, or risk large financial losses. If a product being developed or manufactured in a clean room becomes contaminated, the entire product in the clean room must often be discarded.
Microbial air samplers are used to monitor the level of cleanliness (in terms of viable contamination) in a controlled environment. One or more samplers are positioned about the clean room to collect airborne particulates and organisms (or microorganisms) such as bacteria and fungi. Samplers that run at high flow rates permit air to enter the sampler at such high flow rates that loss of smaller particulates carrying microorganisms is normality (i.e., smaller particulates are not retained in the medium). At the same time high flow rate air samplers only sample for a short time period and relay on a short snapshot of the condition of the area. Samplers running at 28.3 LPM (liters per minute) must operate for a longer period of time than a unit running at 322 LPM. In doing this, they sample a broader spectrum of the drug fill time and present superior data as the sample time takes a larger snapshot of the operation. Samplers that run at 28.3 LPM also provide the ability to capture more smaller particulates that may be lost due to dynamic drag (or an umbrella affect) in higher flow rate units.
Air sampling systems are generally known, and an air sampling system is offered by Veltek Associates, Inc. known as SMA (Sterilizable Microbiological Atrium) Microbial Air Sampler System. One such system is shown in U.S. Pub. No. 2011/0167931, filed Jan. 12, 2010, and U.S. Pat. No. 7,940,188, filed Jul. 26, 2010, the entire contents of which are hereby incorporated by reference. As noted in those applications, the air sampler system includes a controller connected to a vacuum pump to control the flow of air to air sampler devices located in the clean room.
A prior art air sampler device 5 is shown in FIGS. 1(a), (b), which is offered by Veltek Associates, Inc. The assembled air sampler device 5 includes a top plate 10 with holes 11 and a bottom plate 14. The top plate 10 has a flat section and an outer side. The flat section forms the top surface of the top plate 10 and extends substantially horizontally when in use. The openings pass through the flat section. The outer side extends downward to be substantially orthogonal to the flat section. The outer side has a single uniform thickness that extends the entire circumference of the top plate 10. The outer surfaces of the top plate 10 and the bottom plate 14 are flat and smooth. The bottom plate 14 is sized and shaped substantially the same as the top plate 10. Though the device 5 is shown as circular, other shapes may be used.
In operation, the top plate 10 is removed, a Petri dish is placed on the bottom plate 14, and the top plate 10 is replaced on the bottom plate 14. A vacuum tube is attached to the air port 22. Air is then sucked in through the holes 11 in the top plate 10, so that the air strikes a test medium contained in a Petri dish, which is inside the air sampler device 5 between the top plate 10 and the bottom plate 14. The air exits through the air port 22 and vacuum tube. At the end of the testing period, the top plate 10 is again taken off of the bottom plate 14, the Petri dish is removed, and the top plate 10 is replaced. The Petri dish can then be analyzed to determine the level of cleanliness of the clean room.
The entire device 5 is metal so that the device 5 can be sterilized by heat, steam, Vaporized Hydrogen Peroxide (VHP) or Ethylene Oxide (ETO). The Petri dish has a diameter of about 3.5 inches. The top plate 10 has an outer diameter of 4.5 inches. There are twelve holes 11 positioned within about a circular area having a 3 inch diameter, and each hole 11 has a diameter of about 0.5 inches.
However, the sides of the top plate 10 are smooth and the top plate 10 is relatively heavy, specifically, 1 pound, 4.2 ounces. Consequently, the top plate 10 can be difficult to grasp by a person inside the clean room who is wearing gloves.